feat: Add parseJson Handlebars Helper to Support Processing Nested JSON Data (#31998)

Co-authored-by: AdrianKoszalka <adrian.koszalka@techminers.com>

superset-frontend/plugins/plugin-chart-handlebars/src/components/Handlebars/HandlebarsViewer.tsx

@@ -99,5 +99,18 @@ Handlebars.registerHelper(
   },
 );
 
+// usage: {{parseJson jsonString}}
+Handlebars.registerHelper('parseJson', (jsonString: string) => {
+  try {
+    return JSON.parse(jsonString);
+  } catch (error) {
+    if (error instanceof Error) {
+      error.message = `Invalid JSON string: ${error.message}`;
+      throw error;
+    }
+    throw new Error(`Invalid JSON string: ${String(error)}`);
+  }
+});
+
 Helpers.registerHelpers(Handlebars);
 HandlebarsGroupBy.register(Handlebars);

superset-frontend/plugins/plugin-chart-handlebars/src/plugin/controls/handlebarTemplate.tsx

@@ -20,8 +20,9 @@ import {
   ControlSetItem,
   CustomControlConfig,
   sharedControls,
+  InfoTooltipWithTrigger,
 } from '@superset-ui/chart-controls';
-import { t, validateNonEmpty } from '@superset-ui/core';
+import { t, validateNonEmpty, useTheme, SafeMarkdown } from '@superset-ui/core';
 import { CodeEditor } from '../../components/CodeEditor/CodeEditor';
 import { ControlHeader } from '../../components/ControlHeader/controlHeader';
 import { debounceFunc } from '../../consts';
@@ -33,13 +34,48 @@ interface HandlebarsCustomControlProps {
 const HandlebarsTemplateControl = (
   props: CustomControlConfig<HandlebarsCustomControlProps>,
 ) => {
+  const theme = useTheme();
+
   const val = String(
     props?.value ? props?.value : props?.default ? props?.default : '',
   );
 
+  const helperDescriptionsHeader = t(
+    'Available Handlebars Helpers in Superset:',
+  );
+
+  const helperDescriptions = [
+    { key: 'dateFormat', descKey: 'Formats a date using a specified format.' },
+    { key: 'stringify', descKey: 'Converts an object to a JSON string.' },
+    {
+      key: 'formatNumber',
+      descKey: 'Formats a number using locale-specific formatting.',
+    },
+    {
+      key: 'parseJson',
+      descKey: 'Parses a JSON string into a JavaScript object.',
+    },
+  ];
+
+  const helpersTooltipContent = `
+${helperDescriptionsHeader}
+
+${helperDescriptions
+  .map(({ key, descKey }) => `- **${key}**: ${t(descKey)}`)
+  .join('\n')}
+`;
+
   return (
     <div>
-      <ControlHeader>{props.label}</ControlHeader>
+      <ControlHeader>
+        <div>
+          {props.label}
+          <InfoTooltipWithTrigger
+            iconsStyle={{ marginLeft: theme.gridUnit }}
+            tooltip={<SafeMarkdown source={helpersTooltipContent} />}
+          />
+        </div>
+      </ControlHeader>
       <CodeEditor
         theme="dark"
         value={val}